This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. A thorough molecular understanding is sought for how influenza virus infects a host. To this end, we have cloned and expressed influenza viral proteins from historical, contemporary and pandemic stains. To date we have crystallized soluble forms of both hemagglutinin (HA) and neuraminidase (NA) from a broad range of viruses and new targets are in the pipeline, including the pandemic strains of 2009-2010. Determination of these structures has public health interest for designing effective vaccines and antivirals, also will provide valuable insight to the rapid evolution of influenza coat proteins. In addition, we have raised and purified monoclonal antibodies (mAbs) to these coat proteins. Structural characterization of these mAb/antigen interactions will provide important information about antibody recognition that will assist in designing the next generation of influenza vaccines.